Refrigeration



Feb. 9, 1943. c. c, 'CQQNS ETAL 2,310,760

? REFRIGERATION Filed Feb. 5, 1940 H l INVENTORS cl ll'tl C1 C0 0123 & Clarence GZPuc/ky ATTORNEY starting torque.

Patented Feb.- 9, 1943 UNITED STATES PATENT OFFICE REFRIGERATION Curtis 0. Coons and Clarence G. Puchy, North Canton, Ohio, assignors to The Hoover Company, North Canton, Ohio Application February 5, 1940, Serial No. 317,384

12 Claims.

This invention relates to the art of refrigeration and more particularly to a novel absorption refrigerating system involving unique control and regulating features.

This invention particularly relates to threefluid absorption refrigerating systems of the type in which a fluid circulating motor is hermetically sealed within the system in order to circulate the fluids therein contained.

In previous constructions considerable dimculty has been experienced due to the fact that ordinary control mechanisms simultaneously energized the circulator and the heater for the boiler, thus initiating circulation of the inert gas and absorbing solution before the boiler heater has had an opportunity to heat the boiler and its contents to the point where refrigerant vapor. is evolved therefrom. .This represents a direct loss of electrical energy and a direct heat loss by reason of the fact that absorbing solution is circulated through the boiler, cooled in the absorber and returned to the boiler without having refrigerant vapor evolved therefrom. Moreover, the inert gas circulates through the absorber in contact with the liquid previously heated to some extent in the boiler, is heated and after being heated in such fashion the inert gas is propelled through the evaporator which isin the refrigerated space, thus further warming that space and effectively increasing the ultimate refrigerating load upon the apparatus.

In domestic refrigerating systems of the type herein under consideration the fluids may be circulated by means of a very small electrical motor which is hermetically sealed within the system. Such motors are eiilcient and operate satisfactorily on an electrical input of a very few watts. However, they do not develop a high running or The running torque is sufficient for all practical purposes but it is desirable to provide some means to increase the starting torque of such small electrical motors.

Accordingly, it is a principal object of the present invention to provide a three-fluid absorption refrigerating system of the type utilizing a heater for the boiler and a power driven fluid circulator with a control mechanism which will permit theboiler to be heated to the point of evolving'refrigerant vapor prior to energization of the P to bring the motor as a whole up to its eflicient operating temperature.

It is another object of the present invention to provide an absorption refrigerating system of the type above referred to in which the circulator is energized when the temperature of a portion of the apparatus definitely indicates that vapor is being produced in the boiler by the boiler heater. Furthermore, it is an object of the present invention to provide a means whereby the circulator once energized operates upon a starting cycle which produces high torque and high heat in the windings in order to insure starting of the motor and to bring the same up to operating temperature. I

It is another object of the invention to provide means arranged'to change the circulating motor from a starting circuit to a running circuit in response to a condition of the apparatus indicating that the condition of the system is such that the motor will operate dependably on a running circuit.

Other objects and advantages of the invention will become apparent as the description proceeds when taken in connection with the accompanying drawing in which:

Figure 1 is a diagrammatic representation of an absorption refrigerating system embodying the present invention, and

Figure 2 is a partial diagrammatic representation of a modified form of the invention.

Referring now to the drawing in detail and first to Figure 1 thereof, there is illustrated a three-fluid absorption refrigerating system comprising a boiler B, an analyzer D, an air-cooled rectifler R, a tubular air-cooled condenser C, an evaporator E, a gas heat exchanger G, a tubular inclined air-cooled absorber A, a liquid heat exchanger L, a solution reservoir S, and a circulating fan F which is driven by an electrical motor M. These elements are suitably connected by various conduits to form a plurality of gas and liquid circuits constituting a complete refrigerating system to which reference will be made in more detail hereinafter.

The above described refrigerating system will be charged with a suitable absorbent, such as water, a suitable refrigerant, such as ammonia, and an inert pressure equalizing medium preferably a dense inert gas like nitrogen.

The boiler B is arranged to be heated by a gas burner H which will be described in more detail hereinafter. The application of heat to the boiler B generates refrigerant vapor from the solution therein contained. The vapors so generated pass upwardly through the analyzer D in The solution reservoir 8 is vented by means of a conduit it which connects to the suction conduit ll of the circulating fan F. The conduit l5 extends between the suction side of the fan F and the upper portion of the absorber A.

The lean solution is conveyed from the reservoir S to the conduit l8 adjacent its point of connection with the absorber A by means of-'a gas lift pumping conduit to. Pumping gas is supplied to the conduit "by means of a conduit I! which is connected between the discharge conduit l8 of the circulating fan F and the gas lift pump I8 below the liquid level normally prevail= ing therein and in the solution reservoir S.

The lean solution flows downwardly through the absorber A in counterflow relationship to a rich mixture of inert gas and refrigerant vapor which is supplied to the bottom portion of the absorber from the evaporator in a manner to be described hereinafter.

In its traverse through the absorber the lean solution absorbs refrigerant vapor from the gas mixture flowing therethrough and the resulting heat of absorption is rejected by the cooling fins to cooling air flowing over the exterior walls of the absorber vessel.

The strong solution thus formed in the absorb er is conveyed therefrom to the upper portion of the analyzer D by way of the conduit 89, the liquid heat exchanger L, and a conduit 2t, thus completing the absorption solution circuit.

Lean inert gas is formed in the absorber A by the absorption of refrigerant vapor and is then conveyed from the upper portion of the absorber to the suction side of the circulating fan F by means of the conduit ill. The inert gas is placed under pressure by the fan F and is then conveyed therefrom to the lower portion of the evaporator E by way of the conduit 18, the outer path of the gas heat exchanger G and an evaporator gas supply conduit 22. I

The refrigerant vapor which is supplied to the condenser C is liquefied therein by heat exchange relationship with atmospheric air and is then conveyed therefrom to the bottom portion of the evaporator it by way of the conduit 22 and aconduit 26 which includes a downwardly ex= tending U-shaped looped portion which is designed to carry a liquid seal and a pressure balancing column of the liquid refrigerant. The conduits 28 and 2d are vented by means of a conduit 25 to the rich gas side of the gas heat enchanger G. As a result of this construction the pressure prevailing in the condenser and the condenser side or the conduit 24: is that prevailing on the discharge side of the evaporator whereas the pressure prevailing on the discharge side'of the conduit 28 is that prevailing at the inlet to the evaporator. This pressure diflerence is compensated bya pressure balancing liquid col which is supported in the condenser side oi the conduit; 2%.

The evaporator E may be of any desired type of construction. However, as diagrammatically illustrated herein, it is of the type in which the high velocity gas stream flowing through the evaporator serves to sweep or drag liquid refrigerant upwardly therethrough as it is evaporating to produce refrigeration. A preferred construction of this type evaporator is disclosed and claimed in the co-pending application of Curtis 0. Coons and William H. Kitto, Serial No. 220,189, filed July 20, 1938.

An anti-blocking and overflow drain 2! is connected between the upper portion of the bottom conduit in the evaporator E and the strong solution return conduit i9.

The liquid refrigerant supplied to the bottom portion of the evaporator E meets a high velocity gas stream flowing upwardly therethrough with the result that the liquid refrigerant is propelled upwardly through the evaporator as it is evaporating into the gas stream to produce useful refrigeration.

The top portion of the evaporator is provided with a large diameter finned box-cooling conduit 28 into which both the liquid and gas discharge. The gas flows at a slow rate through this conduit, hence the same is inclined rearwardly in order to permit liquid to flow by gravity. The resulting rich gas and unevaporated'material in the evaporator is conveyed from the conduit 28 into the rich gas side of the gas heat exchanger G by means of a conduit 29. After traversing the rich gas side of the gas heat exchanger the rich gas and unev'aporated material is drained therefrom into the bottom portion of the absorber A by means of the conduit it. Thus, the conduit 3!? serves as a rich gas return conduit and as an evaporator drain. The rich gas then flows upwardly through the absorber A in counterfiow relationship with the lean solution flowing downwardly therethrough in the manner heretofore described.

It will be noted that with the construction. thus provided evaporator drainage is conveyed to the conduit it in a manner such that it cannot reach the circulating fan and the fan is so connected to the absorber that lean solution cannot be conveyed thereinto from the lean solution supply lines.

The circulating motor fan assembly comprises a conventional gas i'an which is sealed within the ho Fahd arranged to receive gas from the suction conduit ill and to discharge the same into the discharge conduit it in a conventional man ner. This fan is driven by an electrical motor of the induction type which includes a rotating part hermetically sealed within the system within a motor shell 82 and which is driven by a suitable field construction 88 which is mounted upon the exterior wall of the shell 82.

The heater H for the boiler B is supplied with fuel through a suitable gas supply conduit 35 which includes the solenoid valve V and a suitable thermostatic safety cut-on device so which will completely shut on the supply of flame tothe heater H upon complete flame failure thereat. A small lay-pass Si is provided around the solenoid valve V in order to provide a small pilot or ignition flame upon the burner H when the valve V is in closed position.

Electrical energy for the valve V and motor M is supplied from a suitable pair of electrical condoctors Q6 and (it. a

The conductor (it) connects directly to a therrh -static control mechm :32 01 a conventional type which consists essentially of a thermostatic switch arranged to respond to the temperature at or adjacent the evaporator E by means of a capillary conduit 43 and thermostatic bulb 44.

The stator winding 45 of the electrical motor M is indicated diagrammatically thereabove in order to facilitate understanding of the invention. One side of the winding 45 is connected by means of an electrical conductor 45 to the solenoid valve V and the conductor 45 is connected by means of a conductor 41 to the thermostatic switching mechanism 42.

The conductor 4| is connected to a conductor 45 which is connected between the solenoid valve V and the movable contact 45 pf a thermostatic snap-acting toggle switch 55. The stationary contact of the switch 55 is connected by means be actuated by means of a thermostat 55 which is.

positioned to be influenced by the thermal condition of the vapor conduit just beyond the finned rectifier portion thereof.

The thermostatic switch mechanism 54 is arranged to be actuated by a thermostat 5| which is also positioned to be influenced by the thermal condition of the conduit II but at a point between the condenser and the thermostatic element 55. The thermostatic switch mechanism may be enclosed in suitable housing, if desired, as

indicated in dotted lines.

The operation of the apparatus except insofar as the same has already been described in describing the refrigerating mechanism per se is as fol lows: When the apparatus is originally installed all portions thereof will be substantially at atmospheric temperature wherefore the thermostatic switching mechanism 42 will have closed the circuit between the conductors 45 and 41, the switch 55 will be in open circuit position by reason of the thermostat 55 assuming the dotted line position indicated in Figure 1 and the switch contact 53 will be in contact with the stationary contact 55 by reason of the thermostat 5| being in the dotted line position indicated in Figure 1. Therefore, as soon 'as the apparatus is connected to suitable sources of electrical energy, the valve V will open due to the energization of the conductors 45 and 45, and a full flame will be carried upon the burner which will serve to heat the boiler B and its contents but the motor M will not be operated because of the open-circuit position existing at the switching mechanism 55. Heat will continue to be applied to the boiler B from the burner H for a sufllcient period of time to bring the same to the boiling point and. to evolve refrigerant vapor without meeting the losses attendant upon circulation of the inert gas and solution at this time. Refrigerant vapor will then begin to flow through the conduit II to the condenser C and will very quickly heat the conduit sufllcientlywto actuate the thermostat 55 to the 'solidline position indicated in Figure 1 which will close the circuit between the contacts 45 and 5|, thereby energizing the circulator motor through the following circuits: 45,42, 41, 45,. 75

lower half of 45 as viewed in Figure 1, 55, 55, 53, 52, 5|, 45, 45, 4|. This circuit will energize only a portion of the motor windings wherefore the same will take a very high currentwhich will 5 provide the motor with a starting torque, two to three times normal, and will also generate a rather large quantity of heat. Such a motor winding arrangement is not efficient but it is not objectionable as a starting device. The high starting torque provided by the circuit just described will insure that the motor will start immediately the thermostat 55 flexes to the closed circuit position and will also produce a large quantity of heat which will serve quickly to heat 5 the motor to its operating temperature and will also quickly soften the lubricant in the motor bearings in the event that the same is stiff or will not flow readily.

The above described operation of the apparatus will continue for a short period of time until the higher portion of the conduit II with which the thermostat 5| is in heat exchange relation has been heated by the hotvapor flowing therethrough. When this occurs the thermostatic element 5| shifts from the dotted line position shown in Figure 1 to the solid line position. thus snapping the contact 55 from its position against the contact 55 to a position against the contact 55. The entire motor winding is now energized as the current previously supplied to the switch arm 53 now flowsthrough 53, 55, 51 and throughout the niotor winding 45. This is the running condition of the motor in which the current consumed by the same is much lower than that consumed on starting and in which the motor operates at its highest efficiency. Under these conditions the torque produced by the motor is lower than that produced in the starting circuit but it is ample for operating conditions.

The above described circuits will be maintained until such time as the temperature at or adjacent the evaporator has reached the value for which the thermostatic control mechanism 42 is set at which point the mechanism 42 will open the electrical circuit between the conductors 45 and 41.

After de-energization of the valve and motor by the thermostatic control mechanism 42 the conduit II will quickly cool and the thermostatic elemen s 55 and 5| will move to the dotted line position indicated in Figure 1, thereby opencircuiting the switch 55 and shifting the movable contact arm 53 into engagement with the statirnary contact 55 to condition the apparatus for the next cycle of operation.

In Figure 2 there is illustrated a modified form of the invention. The invention of Figure 2 is designed and intended to be utilized with a refrigeratlng system identical with that disclosed in Figure 1, hence only the control mechanism and its immediately associated portions of the apparatus have been illustrated in this figure. Certain portions of the apparatus illustrated in Figure 2 are identical with apparatus previously illustrated and described in connection with Figure 1 and they are therefore given the same reference characters primed. I

As may readily be seen from an inspection of Figure 2, the heating arrangement for the boiler is identical .with that described in connection with Figure 1 as is the motor fan arrangement. Onl the control mechanism differs.

. In the form of the invention in Figure 2 electrical energy is supplied to the apparatus through a pair of electrical conductors 6B and GI. Electrical conductor 60 connects directly to the thermostatic control switch 42' which is then connected by means of a conductor 63 to a conductor 62 which connects the solenoid valve V' and one end of the motor field winding 45'. The conductor 6| connects directly to the valve V' and is connected by means of a conductor 64 to the movable contact 65 of a snap acting toggle switch 66 arranged to be actuated by thermostatic bellows 61. The bellows Bl is provided with a capillary tube and bulb assembly 68 which is positioned in heat exchange relationship with the vapor line H above the rectifier R.

The activecontact 69 of the switch assembly 66 is connected to the movable contact III of a second snap acting thermostatic switch II by means of an electrical conductor 12. The left hand contact 13 of the switch H is connected by means of an electrical conductor I4 to the mid point of the motor field winding 45' and the contact 15 of the switch H is connected to the opposite end of the motor field winding 45' by means of an electrical conductor 16, thus completing the electrical control circuit of the apparatus. The switch II is actuated by a thermoe static bellows 18 which is arranged to be responsive to the temperature of the motor shell 32' by means of a capillary tube 19 which connects the bellows to a bulb 80 positioned against the bottom wall of the shell 32'.

This form or the invention operates in substantially the same manner as that described in connection with Figures 1 and 2 except that the circulating motor in this instance is shifted from the starting cycle to the running cycle in response to the temperature of the motor shell 32' rather than inresponse to the temperature condition of a portion of the vapor line connecting the analyzer and condenser and remote from the analyzer.

The advantage of this form of the invention is that in installations using a rather stiff lubricant for the motor it .is desirable to maintain the motor on the operating and starting cycle until. the motor assembly has warmed up sumciently to operate efliciently and to soften the lubricant to the point where it does not impose an appreciable drag on the rotating part of the motor before shifting the same to the running winding which operates with a low torque but with a high electrical efliciency. This form of the invention is also desirable for installations in cool climates because it prevents operation of the motor on its running circuituntil it has reached its normal operating temperature.

Therefore, 'in accordance with this form of the invention a demand tor refrigeration will cause energization of the solenoid valve V through the circuits 60, 42', 63, 62, V 6!.

After the boiler has been brought into operating condition and has heated the conduit ii the switch 66 will close the circuit between the conductors 641 and 72 by which the motor starting cycle will be completed through the following circuit: 68, t? 63, $2,. lower half of the winding 35, conductors l6, ?3, iii, 72, $9, $5, ti.

After the motor has warmed up appreciably the bellows it? through its capillary tube and bulb assembly 79 and Bi! responds to an increase in temperature on the part of the motor shell 32' and eXpands thus actuating the snap-acting-switoh mechanism ii to break the circuit at the point 53 and to close the circuit at the point thus ener= sizing the entire running winding and placing the apparatus in normal running condition.

Both forms of the invention herein disclosed provide a highly eficient and desirable control arrangement in that energization of the fluid circulator is not initiated until the boiler is brought into operating condition, thereby obviating heat losses due to circulation of the inert gas and absorption solution as well as the electrical loss entgiled by useless operation of the motor ran uni Moreover, a high torque starting'circuit is provided to bring the motor quickly into eflicient operating condition after which the motor is shifted to its low torque high efliciency running circuit in response either to an increase in the Y temperature on the part of a portion 01' the vapor line remote from the boiler or in response to a change in the temperature condition of the motor shell construction.

While we have shown but one embodiment of our invention, it is to be understood that this embodiment is to be taken as illustrative only and not in a limiting sense. We do not wish to be limited to the particular structure shown and described but to include all equivalent variations thereof except as limited by the claims.

We claim: I

1. Absorption refrigerating apparatim including a generator, a heater for said generator, a fluid circulator, power operated means for driving said circulator refrigeration demand responsive means for controlling said heater, means responsive to a change in the condition of a portion of said apparatus reflecting a change in the operating condition of said heater for energizing starting connections for said power operating means, and means for subsequently deenergizing circulator,

said starting connections and for energizing running connections for said power operated means.

2. Absorption refrigerating apparatus including a generator, a heater for said generator. a fluid power operated means for driving said circulator refrigeration demand responsive means for controlling said heater, means responsive to a change in the condition of a first portion of said apparatus reflecting a change in the operating condition of said heater for energizing starting connections for said power operated means, and means for subsequently deenergizing said starting connections and for energizing running connections for said power operated means in response to a change in the condition of a second portion of the apparatus.

3. Absorption refrigerating apparatus including a generator, a condenser, an evaporator, an absorber, and a fluid circulator connected in circuit, a motorior driving said circulator, said circuit including refrigerant vapor conducting means connecting said generator to said condenser, a heater for said generator, means for controlling the operation of said heater in response to refrigeration demand, star-ting connections for said motor, means responsive to the temperature of said vapor conducting means for energizing said starting connections, running connections for said frigerant vapor is discharged from said generator,

frigerant vapor is discharged from said generator,

denser, a heater for said generator, means for controlling the operation of said heater in response to refrigeration demand, starting connections for said motor, means responsive to the temperature of said motor conducting means for energizing said starting connections, running connections for said motor, and means responsive to the temperature of a portion of said vapor conducting means further removed from said generator than the portion thereof to which said starting connections energizing means is responsive for de-energizing said starting connections and for energizing said running connections.

5. Absorption refrigerating apparatus including a generator, a condenser, an evaporator, an absorber, and a fluid circulatcr connected in circuit, a motor for driving said circulator, said circuit including refrigerant vapor conducting means connecting said generator to said condenser, a heater for said generator, means for controlling the operation of said heater in response to reiri'geration demand, starting connections for said motor, means-responsive to the temperature of said vapor conducting means for energizing said starting connections, running connections for said motor, and means responsive to the temperature of said motor for de-energizing said starting connections and for energizing said running connections after said motor has been brought into operating condition.

6. Absorption refrigerating apparatus including a generator, a conduit for conducting refrigerant vapor away from said generator, a fluid circulator, a motor for driving said fluid circulator having a field winding including high torque and. high heating starting connections and running connections, a heater for said generator, means for rendering said heater operative and inoperative in response to refrigeration demands, means for energizing said starting connections when re=- frigerant vapor is discharged from said generator, and means for subsequently de-energizing said starting connections and for energizing said running connections.

7. Absorption refrigerating apparatus including a generator, a conduit for conducting refrigerant vapor away from said generator, a fluid circulator, a motor for driving said fluid circulator having a field winding including high torque and high heating starting connections and running connections, a heater for said generator, means for rendering said heater operative and inoperative in response to refrigeration demands, means for energizing said starting connections when reand means responsive to the thermal condition of a portion of said vapor conduit removed from said 7 generator for de-energizing said starting connections and for energizing said running connections. 8. Absorption refrigerating apparatus including a generator, a co'nduitfor conducting refrigerant vapor away from said generator, 9. fluid circulator, a motor for driving said fluid circulator having 'a fleld winding including high torque and high heating starting connections and running connections, a heater for said generator, means for renderingsaid heater operative and inoperative in response to refrigeration demands, means for energizing said starting connections when reand means for de-energizing said starting connections and for energizing said running connections when said motor has reached its operating temperature. 16

9. An absorption refrigerating system comprising an inert gas circuit including an evaporator and an absorber, a solution circuit including a boiler and said absorber, means for liquefying refrigerant vapor produced in said boiler and for supplying the liquid to said evaporator, means for circulating inert gas and absorption solution through said inert gas and absorption solution circuits respectively, a motor for driving said last mentioned means having starting and running connections, a heating means for said boiler, control means for energizing and deenergizing said heater in response to refrigeration demand, means for energizing said starting connections after said boiler has begun to discharge refrigerant vapor, and means for subsequently energizin said running connections.

10. An absorption refrigerating system comprising an inert gas circuit including an evaporator and an absorber, a solution circuit including a boiler and said absorber, means for liquefying refrigerant vapor produced in said boiler and for supplying the liquid to said evaporator, means for circulating inert gas and absorption solution through said inert gas and absorption solution circuits respectively, a motor for driving said last mentioned means, a heating means for said boiler, said motor including a field winding having a connection intermediate its ends whereby only a portion thereof maybe energized to provide for high starting torque and rapid initial motor heating, control means for rendering said heater operative and inoperative in accordance with refrigeration demand, means for connecting said intermediate connection and one end of said winding to a source of electrical energy after said boiler has been placed in operation by said heater, and means for subsequently disconnecting said intermediate connection and for connecting the other end of said winding to said source of electrical energy.

11. Absorption refrigerating apparatus including a generator, a condenser, an evaporator, an absorber, and a fluid circulator connected in circuit, a motor for driving said fluid circulator, said circuit including refrigerant vapor conducting means connecting said generator to said condenser, a heater for said generator, means for controlling the operation of said heater in response to refrigeration demand, starting connections for said motor, means for energizing said starting connections in time delayed relationship with the operation of said heater, running connections for said motor, and means responsive to the temperature of said vapor conducting means for de-energizing said starting connections and for energizing said running connections.

12. Absorption refrigerating apparatus including a generator, a heater for said generator, 9. fluid circulator, power operated means for driving said circulator, refrigeration demand responsive means for controlling said heater, means responsive to a change in the condition of a portion of said apparatus reflecting a change in the operating condition of said heater for energizing starting connections for said power operated means in timed delayed relationship with said change in the operating condition of said heater, and means for subsequently de-energizing said starting connections and for energizing running connections for said power operated means.

CURTIS C. COONS. CLARENCE G. PUCEY. 

